Mimicking Experiment Study On Formation Mechanism Of Fibrous Calcite Nano-crystals

Biomineralization is a course of which some inorganic minerals ions, which in the different parts of organism, are effected by organic matrix in some physical-chemical conditions, go through the phases of nucleation, growth and phase-change, are controlled by chemistry, space and structure of organism, and finally form organic minerals aggregation.The aim of this study is to discuss the possible formation mechanism (biomineralization) of Fibrous Calcite Nano-crystals in the Loess. Using different synthesis methods (including carbonation, micro-emulsion, reverse micelle and normal micelle) to synthesize Fibrous Calcite Nano-crystals which are similar to the calcite in the Loess. Studying the effect of different experimental conditions (including temperature, additive, solvent and reactant concentration, etc.) on the morphology of synthesized calcium carbonate, and using TEM and XRD to analyze morphologies and components of synthesized samples respectively, the conclusions thereinafter:(1) Using carbonization method to synthesize calcite, the results suggested that the adding quantities and time of surfactant and reaction temperature had great influence on the morphology of calcium carbonate. Appropriate adding quantities of surfactant was in favor of forming calcium carbonate with uniform diameters; the longer time surfactant was added, the longer diameter calcium carbonate was gotten; the lower temperature we set, the shorter diameter of calcium carbonate we got, and the better dispersive the powder we got.(2) Using CTAB/heptane/water system to synthesize calcite, the results suggested that different adding quantities of surfactant and heptane and different reactants concentration would form calcite with different morphology.(3) Using SDBS/organic solvent/water system to synthesize calcite, the results suggested that different adding quantities of surfactant, different kinds of organic solvent and different reaction temperature had influence on morphology and polymorphies of calcium carbonate.(4) Using green grass and extracts of grass to simulate natural mineralization, get nano-rod calcium carbonate was gotton. Under natural mineralization and using different kinds of organic material, different morphology of calcium carbonate was gotton. Then a conclusion was gotton, which is that organic substance has great influence on the formation process of Fibrous Calcite Nano-crystals in the Loess, but the idiographic mechanism need be studied farther.